Hi Lee, On Wed, Sep 12, 2018 at 10:41 AM Lee Jones <lee.jones@xxxxxxxxxx> wrote: > On Wed, 12 Sep 2018, Alexandre Belloni wrote: > > On 11/09/2018 23:54:40+0100, Lee Jones wrote: > > > > > http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-6438-32-bit-ARM926-Embedded-Microprocessor-SAM9G45_Datasheet.pdf > > > > > > > > > > USART doc starting p572, registers p621. > > > > > > After looking at the datasheet, I don't see any reason why one of the > > > two drivers can't be selected using different compatible strings. > > > > Because there is only one IP and we don't use the device tree to selecet > > linux specific drivers. > > We do it all the time. There are loads of MFDs (def: same IP, with > different functions) which have separate compatibles for their various > functions. If you wish this IP to operate as an SPI controller, it > should have an SPI compatible, if you wish it to operate as a U(S)ART, > then it should have a UART compatible. It's what we do for most of > the other MFDs in the kernel. There is a big difference: MFD functions are(more or less) independent functions, which can be used at the same time. It makes perfect sense for a single IP block that has both SPI and UART interfaces, that can be used at the same time. In this case, there is a single piece of hardware that can perform different functions, but not at the same time. Performing a different function means configuring the hardware for that function, hence using a different driver (from a different subsystem). Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
